UPLIFT OR SUBSIDENCE?: VOLCANIC GEOLOGY ON THE 1905-06 GALAPAGOS EXPEDITION OF THE CALIFORNIA ACADEMY OF SCIENCES

For 17 months during 1905-06, the California Academy of Sciences (CAS) sent out a multidisciplinary expedition from the museum in San Francisco, California, to the Galapagos Islands, Ecuador, aboard the 89-foot former U.S. Coast and Geodetic Survey schooner Earnest renamed the Academy. In addition to seven specialist field collectors in ornithology, herpetology, mammalogy, entomology, and botany, the expedition included Washington Henry Ochsner (1882-1927) who served as the expedition’s geologist. Ochsner investigated the volcanic geology of the equatorial Galapagos Islands in addition to collecting fossils and modern shells. The volcanic nature and young geologic age of the archipelago were described by Charles Darwin (1809-1882) based on his visit during the voyage of HMS Beagle (1831-1836). Georg Baur (1859-1898), a German-trained employee of Yale University, Clark University, and the University of Chicago, concluded prior to his visit to the Galapagos Islands in 1891 that the islands were remnant mountain peaks resulting from subsidence of a former continental landmass. Baur’s fieldwork merely confirmed his preconceived notions about the origin of the islands. Ochsner’s year-long participation in the 1905-06 expedition (as documented in his unpublished field notes and unpublished manuscripts in the CAS Archives) resulted in support for Baur’s subsidence hypothesis over the Darwinian uplift hypothesis. Modern sea floor imaging confirms the archipelago has never been connected by land bridges or a landmass to the South American continent. Ochsner’s lines of reasoning for siding with Baur over Darwin are instructive for understanding the interplay between field observations and preconceived notions in the history of geology. Ochsner' geological observations and conclusions stand in contrast to the clear vindication by the 1905-06 expedition of Charles Darwin's Galapagos biological observations and his mechanism of natural selection. Ochsner's Galapagos geological observations have been supplanted by modern support for Darwin. The enduring legacy of the 1905-06 Galapagos expedition is not diminished by the controversy between uplift and subsidence in the geologic history of the archipelago.